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Adjustment and Calibration
Adjustment and Calibration
Precautions
Use the adjustment functions only if you are fully aware of their consequences.
Wrong adjustment values will lead to false measurement values and in
consequence these false values lead to hazards for patients.
Definitions
Adjustment
An adjustment is a process in which properties of a measuring device are changed in that way that its scale or
display reads the same as an reference device or standard.
Calibration
Calibration is the process of establishing the relationship between a measuring device and the units of
measure. This is done by comparing a device or the output of an instrument to a standard having known
measurement characteristics. For example the length of a stick can be calibrated by comparing it to a
standard that has a known length. Once the relationship of the stick to the standard is known the stick can be
used to measure the length of other things. Adjustments are checked by performing a calibration.
General
According to ISO 10012-1
“General Quality Assurance Requirements for Measuring Equipment" the error
attributable to calibration should be as small as possible. In most areas of measurement, it should be not
more than one third and preferably one tenth of the permissible error of the confirmed equipment when in
use. In other words the accuracy of the references to adjust or calibrate the HDM must have at least a tree
times higher accuracy.
After a channel has been adjusted it is necessary to calibrate it afterwards. If inconclusive or
incomprehensible values are shown in the display it is highly recommended to do a calibration.
The procedure of calibration and adjustment is slightly different for each channel. Proceed with an
adjustment only if you have fully understood the procedure.
•
Conductivity is adjusted only at one sampling point. No further points are needed due to the high
linearity of the conductivity probe.
•
The temperature sensor does not drift. Normally there is no adjustment necessary. The adjustment is
done by using two sampling points.
•
The pressure transducers drift is linear within its tolerances, so there is a tare function (see chapter
"Measuring"). Normally there is no adjustment necessary. The adjustment is done by using seven
sampling points.
•
Due to the kind of their technology it is necessary to adjust pH probes periodically. This is done
using two sampling points.
If you are uncertain of entering the correct adjustment values you can discard the values and cancel the
adjustment procedure at any time.
